Bottom Line:
The deletion of FgPDK1 in F. graminearum resulted in the increase in PDH activity, coinciding with several phenotypic defects, such as growth retardation, failure in perithecia and conidia production, and increase in pigment formation.The deletion of FgPDK1 also prohibited the production of deoxynivalenol (DON) and pathogenicity of F. graminearum, which may resulted from the decrease in the expression of Tri6.Taken together, this study firstly identified the vital roles of FgPDK1 in the development of phytopathogen F. graminearum, which may provide a potentially novel clue for target-directed development of agricultural fungicides.

ABSTRACTPyruvate dehydrogenase kinase (PDK) is an important mitochondrial enzyme that blocks the production of acetyl-CoA by selectively inhibiting the activity of pyruvate dehydrogenase (PDH) through phosphorylation. PDK is an effectively therapeutic target in cancer cells, but the physiological roles of PDK in phytopathogens are largely unknown. To address these gaps, a PDK gene (FgPDK1) was isolated from Fusarium graminearum that is an economically important pathogen infecting cereals. The deletion of FgPDK1 in F. graminearum resulted in the increase in PDH activity, coinciding with several phenotypic defects, such as growth retardation, failure in perithecia and conidia production, and increase in pigment formation. The ΔFgPDK1 mutants showed enhanced sensitivity to osmotic stress and cell membrane-damaging agent. Physiological detection indicated that reactive oxygen species (ROS) accumulation and plasma membrane damage (indicated by PI staining, lipid peroxidation, and electrolyte leakage) occurred in ΔFgPDK1 mutants. The deletion of FgPDK1 also prohibited the production of deoxynivalenol (DON) and pathogenicity of F. graminearum, which may resulted from the decrease in the expression of Tri6. Taken together, this study firstly identified the vital roles of FgPDK1 in the development of phytopathogen F. graminearum, which may provide a potentially novel clue for target-directed development of agricultural fungicides.

Mentions:
The growth of the ΔFgPDK1 mutants was evaluated on PDA, CM, and MM plates. The ΔFgPDK1 mutants showed different growth patterns as compared with that of the wild-type and the complemented mutant strain (ΔFgPDK1-C) (Fig 3A and Table 1). ΔFgPDK1 grew slightly slower than the wild-type parent and the hyphae turned yellow and white on PDA medium. Expression of the yellow pigment-formation genes AurO and AurR2 were significantly up-regulated in the deletion mutants while the expression of red pigment-formation genes AurJ and AurF were not changed significantly (S2 Fig). It is interesting to notice that the deletion mutant grew significantly slower on MM medium with limited carbon source (only sucrose) while it grew normal on CM medium (Table 1 and Fig 3A). Microscopic examination showed that the deletion of FgPDK1 did not change the morphology of aerial hyphae compared with the wild-type parent (Fig 3B). Perithecium can release ascospore (S3 Fig), which is responsible for the sexual reproduction of F. graminearum. Compared to wild-type strain and the complemented strain, the ΔFgPDK1 mutant failed to produce any perithecia on autoclaved wheat seeds (Fig 3C). Conidium is important for F. graminearum to finish asexual reproduction. In the present study, after growing in MBB medium for 7 days, the ΔFgPDK1 mutant failed to produce any conidia (Table 1). All of these growth characteristics were restored in the complemented mutant ΔFgPDK1-C. These results suggested that the deletion of FgPDK1 remarkably impacted both sexual and asexual development of F. graminearum.

Mentions:
The growth of the ΔFgPDK1 mutants was evaluated on PDA, CM, and MM plates. The ΔFgPDK1 mutants showed different growth patterns as compared with that of the wild-type and the complemented mutant strain (ΔFgPDK1-C) (Fig 3A and Table 1). ΔFgPDK1 grew slightly slower than the wild-type parent and the hyphae turned yellow and white on PDA medium. Expression of the yellow pigment-formation genes AurO and AurR2 were significantly up-regulated in the deletion mutants while the expression of red pigment-formation genes AurJ and AurF were not changed significantly (S2 Fig). It is interesting to notice that the deletion mutant grew significantly slower on MM medium with limited carbon source (only sucrose) while it grew normal on CM medium (Table 1 and Fig 3A). Microscopic examination showed that the deletion of FgPDK1 did not change the morphology of aerial hyphae compared with the wild-type parent (Fig 3B). Perithecium can release ascospore (S3 Fig), which is responsible for the sexual reproduction of F. graminearum. Compared to wild-type strain and the complemented strain, the ΔFgPDK1 mutant failed to produce any perithecia on autoclaved wheat seeds (Fig 3C). Conidium is important for F. graminearum to finish asexual reproduction. In the present study, after growing in MBB medium for 7 days, the ΔFgPDK1 mutant failed to produce any conidia (Table 1). All of these growth characteristics were restored in the complemented mutant ΔFgPDK1-C. These results suggested that the deletion of FgPDK1 remarkably impacted both sexual and asexual development of F. graminearum.

Bottom Line:
The deletion of FgPDK1 in F. graminearum resulted in the increase in PDH activity, coinciding with several phenotypic defects, such as growth retardation, failure in perithecia and conidia production, and increase in pigment formation.The deletion of FgPDK1 also prohibited the production of deoxynivalenol (DON) and pathogenicity of F. graminearum, which may resulted from the decrease in the expression of Tri6.Taken together, this study firstly identified the vital roles of FgPDK1 in the development of phytopathogen F. graminearum, which may provide a potentially novel clue for target-directed development of agricultural fungicides.

ABSTRACTPyruvate dehydrogenase kinase (PDK) is an important mitochondrial enzyme that blocks the production of acetyl-CoA by selectively inhibiting the activity of pyruvate dehydrogenase (PDH) through phosphorylation. PDK is an effectively therapeutic target in cancer cells, but the physiological roles of PDK in phytopathogens are largely unknown. To address these gaps, a PDK gene (FgPDK1) was isolated from Fusarium graminearum that is an economically important pathogen infecting cereals. The deletion of FgPDK1 in F. graminearum resulted in the increase in PDH activity, coinciding with several phenotypic defects, such as growth retardation, failure in perithecia and conidia production, and increase in pigment formation. The ΔFgPDK1 mutants showed enhanced sensitivity to osmotic stress and cell membrane-damaging agent. Physiological detection indicated that reactive oxygen species (ROS) accumulation and plasma membrane damage (indicated by PI staining, lipid peroxidation, and electrolyte leakage) occurred in ΔFgPDK1 mutants. The deletion of FgPDK1 also prohibited the production of deoxynivalenol (DON) and pathogenicity of F. graminearum, which may resulted from the decrease in the expression of Tri6. Taken together, this study firstly identified the vital roles of FgPDK1 in the development of phytopathogen F. graminearum, which may provide a potentially novel clue for target-directed development of agricultural fungicides.